Help needed re sunset pics

Is it safe to look through the viewfinder when taking pics of

sunsets? I have a 300mm zoom which I want to use for taking pic of

the sun when its a nice orange colour in the sky. Apart from a small

aperture do I need anything else?

Do I also need ND filters? could I damage the sensor in my 10D by

taking pic at full zoom?

Any tips/suggestions would be appreciated

Regards

Before I say anything please note that my experience is with a D100 and a 70-200mm 2.8 -- however, I doubt that the issue is any different between the Nikon CCD and the Canon CMOS. So here goes.

I have taken some pictures of the sun with a 200mm at 2.8 at sunset in mexico and had no problems whatsoever. Of course, the sun was so close to setting that it was just about to begin eclipsing the horizon. I could get an unobscured picture because I was on top of a dune at it was setting over the pacific -- there were no trees or buildings in my way. I could comfortably view the sun with my naked eye, and I would try to use that as a guide when attempting this kind of photography. Depending on the apeture of the 300mm lens you are using, it may be capable of collecting a lot more light than your eye and, consequently you want to be very careful not to point the lens at the sun until it is right above the horizon (note: this may not be possible if you cannot take the photo from a high vantage point or over a lake or ocean). On another note, when the sun is nearly set, you will want to use a tripod to get the right shutter speed. As to ND filters, you may want to consider them if you want to take pictures of the sun when it is higher than 5 degrees from the horizon or if it cannot be viewed by the naked eye. I would not reccommend this, however, because the light will have a higher angle of incidence to the atmosphere and will not be reddish orange. If you must, however, you should use multiple 8x ND filters (stacked ND filters result in a multiplication of facors, i.e two 8x's is the same as a 64x) and be extremely careful.

The most important thing to consider is where the sun is in the sky. At peak brightness the suns apparent magnitude is on the order of -27 (each smaller integer is a multiple of six brighter so that a first magnitude star is 6 raised to the 28th power dimmer than the sun at peak brightness). When it is on the horizon you may have noticed that its magnitude is much closer to that of the moon for example (this is in fact not true but seems to be the case because the change in the apeture of your eye).

The answer is that you should be 100% fine so long as the sun is low enough in the sky so as to be dim enough to look at with the naked eye. **Do not even point your 300mm and your 10D at the sun before it is extremely obscured by the atmosphere; I would say 0 to 5 degrees above the horizon. Looking through the viewfinder at the sun won't damage your sensor but can DEFINITELY damage your eye if it isn't extremely low to the horizon.

Hope this helps, Justin.

Thanks for a very good and detailed answer Justin. I guess i'll have to wait until for teh perfect conditions.

Regards